This invention relates to roller type conveyor apparatus and more particularly to a power drive system for such conveyors which drive system is particularly adaptable to curved sections of the conveyors.
The food processing industry as well as other industries involved in merchandising and packaging utilize roller type conveyors for movement and distribution of a great variety of package forms. These roller type conveyors can be passive, e.g., those driven by package inertia or gravity, or power driven. Power driven conveyors are used particularly in the horizontal movement of articles from one location to another.
A variety of roller conveyor drive systems are known in the prior art and these drive systems can be adapted to curved conveyor sections. For example, U.S. Pat. No. 1,959,157 discloses a V-belt drive system. A first flange formed to receive one of the angled drive faces of a V-belt is secured to each conveyor roller and a second freely rotating flange for receiving the other angled drive face of the V-belt is mounted opposite to each first flange. If a V-belt is positioned between the flanges, the conveyor roller will rotate as the belt is moved over the pulley formed by the two flanges.
In U.S. Pat. No. 3,369,646, a drive system for a conveyor curve is disclosed wherein a circular drive disc is rotated in the horizontal plane. A plurality of conically shaped rollers extend outwardly from the peripheral edge of the disc and include small wheel-like members attached to their inner ends. The wheel-like members engage the outer edge of the disc surface so that as the disc rotates the members and in turn the rollers rotate.
U.S. Pat. No. 4,096,942 discloses a conveyor drive system wherein a drive belt having a circular cross-section is used to drive pulleys frictionally coupled to the rollers of the conveyor. The drive belt is held against the roller pulleys by adjusting pulleys which are aligned with the roller pulleys for straight sections of conveyor and inclined relative to the axis of the rollers for curved sections of the conveyor.
In these prior art conveyor drive systems, the drive belts are positioned under the conveyor rollers where they are subject to damage and the accumulation of debris which fall between the rollers. These prior art conveyors provide either a positive drive to the rollers which can be dangerous in the event the rollers are inadvertently contacted by personnel working around the conveyors, or they provide a force which rotates the rollers up to a given resistance to provide for an accumulating conveyor.
The conveyor drive systems of the prior art also require considerable floor space when applied to curved conveyor sections which change the direction of movement of articles from a first line of movement to a second line of movement up to 180.degree. displaced from the first line of movement. For example, the drive system shown in previously cited U.S. Pat. No. 3,369,646, which appears to provide the most compact conveyor curve of the cited prior art, includes a rotating disc which occupies considerable space even though only approximately one quarter of the disc is utilized by the drive system. The rotating disc not only occupies additional floor space but also requires separate conveyors external to the conveyor curve to transport articles to and from the conveyor rollers.